Variable displacement compressor

Abstract

A variable displacement compressor having a rotary shaft and a swash plate is described. The swash plate is mounted on the shaft and rotates integrally with the shaft. The swash plate tilts between a maximum inclined angle and a minimum inclined angle and is connected to a plurality of pistons. The inclined angle of the swash plate is altered by the difference between the pressure in a crank chamber and the pressure in a suction chamber. Each piston reciprocates inside a cylinder bore with a stroke determined by the inclined angle of the swash plate and compresses refrigerant gas, which includes oil mist. A spool is arranged adjacent to the swash plate on the shaft. On the shaft, a thrust bearing is provided between the swash plate and the spool, and a radial bearing is provided in the spool. The spool has an opening opposed to the swash plate. Grooves that allow the flow of refrigerant gas into the spool are formed at the opening in the walls of the spool.

What is claimed is: 
     
       1. A variable displacement compressor including a swash plate supported within a crank chamber of a housing on a drive shaft for integral rotation with the drive shaft, the swash plate being tiltable between a maximum inclined angle and a minimum inclined angle with respect to a plane perpendicular to the longitudinal axis of the drive shaft, and at least one piston coupled to the swash plate and disposed in a bore within the housing, wherein rotation of the drive shaft is converted by the swash plate into reciprocating movement of the piston such that gas is drawn from a suction chamber through an inlet valve into the bore during a suction stroke and compressed gas is discharged from the bore through a discharge valve into a discharge chamber during a discharge stroke, and wherein the inclined angle of the swash plate is changed in accordance with the difference between the pressure in the crank chamber and the pressure in the suction chamber to vary the displacement of the compressor, said compressor comprising: a spool disposed adjacent to the swash plate on the drive shaft;   a first bearing disposed on the drive shaft between the swash plate and said spool, said first bearing being arranged to receive axial load generated by and acting on the rotating drive shaft; and   a second bearing disposed on the drive shaft said spool, said second bearing being arranged to receive radial load generated by and acting on the rotating drive shaft.   
     
     
       2. The compressor as set forth in claim 1 further comprising: said spool having an open end and closed end, said open end facing the swash plate and said closed end facing away from the swash plate; and   one of said spool open end and said first bearing having a notch to provide a passage for the gas.   
     
     
       3. The compressor as set forth in claim 2 further comprising a member biasing the spool towards the swash plate. 
     
     
       4. The compressor as set forth in claim 1 further comprising: a passage way for introducing the gas to the suction chamber; and   said spool being arranged to close the passage way when the swash plate is kept at the minimum inclined angle and open the passage way when the swash plate moves from the minimum angle towards the maximum inclined angle.   
     
     
       5. The compressor as set forth in claim 4, wherein said minimum inclined angle of the swash plate is slightly offset from the plane perpendicular to the axis of the drive shaft, and whereby the gas is circulated inside the compressor when the swash plate is kept at the minimum inclined angle. 
     
     
       6. The compressor as set forth in claim 5 further comprising: the drive shaft having a first end and a second end,   said second bearing supporting said first end of the drive shaft; and   a third bearing supporting said second end of the drive shaft to receive radial load generated by and acting on the rotating drive shaft.   
     
     
       7. The compressor as set forth in claim 6 further comprising: a first engaging means provided on the swash plate opposing the first bearing, said first engaging means including one of a projection and a recess; and   a second engaging means provided on the first bearing opposing the swash plate, said second engaging means including the other one of said projection and said recess and engaging the first engaging means.   
     
     
       8. The compressor as set forth in claim 7, wherein said projection has a substantially hemispherical end. 
     
     
       9. A variable displacement compressor including a swash plate supported within a crank chamber of a housing on a drive shaft for integral rotation with the drive shaft, the swash plate being tiltable between a maximum inclined angle and a minimum inclined angle with respect to a plane perpendicular to the longitudinal axis of the drive shaft, and a piston coupled to the swash plate and disposed in a cylinder bore within the housing, wherein rotation of the drive shaft is converted by the swash plate into reciprocating movement of the piston such that gas is drawn from a suction chamber through an inlet valve into the cylinder bore during a suction stroke and compressed gas is discharged from the cylinder bore through a discharge valve into a discharge chamber during a discharge stroke, and wherein the inclined angle of the swash plate is changed in accordance with the difference between the pressure in the crank chamber and the pressure in the suction chamber to move the piston in the cylinder bore with a stroke determined by the inclined angle of the swash plate to vary the displacement of the compressor, said compressor comprising: a spool disposed adjacent to the swash plate on the drive shaft;   a first bearing disposed on the drive shaft between the swash plate and the spool, said first bearing being arranged to receive axial load generated by and acting on the rotating drive shaft;   a second bearing disposed on the drive shaft within the spool, said second bearing being arranged to receive radial load generated by and acting on the rotating drive shaft;   said spool having an open end and a closed end, said open end facing the swash plate and said closed end facing away from the swash plate;   said gas containing lubricant oil mist; and   one of said spool open end and said first bearing having a notch to provide a passage for the gas.   
     
     
       10. The compressor as set forth in claim 9 further comprising a member biasing said spool toward the swash plate. 
     
     
       11. The compressor as set forth in claim 10 further comprising: a passage way for introducing the gas to the suction chamber; and   said spool being arranged to close the passage way when the swash plate is kept at the minimum inclined angle and open the passage way when the swash plate moves from the minimum angle towards the maximum inclined angle.   
     
     
       12. The compressor as set forth in claim 11, wherein said minimum inclined angle of the swash plate is slightly offset from the plane perpendicular to said axis of the drive shaft, and whereby the gas is circulated inside the compressor when the swash plate is kept at the minimum inclined angle. 
     
     
       13. The compressor as set forth in claim 12 further comprising: the drive shaft having a first end and a second end,   said second bearing supporting said first end of the drive shaft; and   a third bearing supporting said second end of the drive shaft to receive radial load generated by and acting on the rotating drive shaft.   
     
     
       14. The compressor as set forth in claim 13 further comprising: a first engaging means provided on the swash plate opposing the first bearing, said first engaging means including one of a projection and a recess; and   a second engaging means provided on the first bearing opposing the swash plate, said second engaging means including the other one of said projection and said recess and engaging the first engaging means.   
     
     
       15. The compressor as set forth in claim 14, wherein said projection has a substantially hemispherical end. 
     
     
       16. A variable displacement compressor including a swash plate supported within a crank chamber of a housing on a drive shaft for integral rotation with the draft shaft, the swash plate being tiltable between a maximum inclined angle and a minimum inclined angle with respect to a plane perpendicular to longitudinal axis of the drive shaft, and at least one piston coupled to the swash plate and disposed in a cylinder bore within the housing, wherein rotation of the drive shaft is converted by the swash plate into reciprocating movement of the piston such that gas is drawn from a suction chamber through an inlet valve into the cylinder bore during a suction stroke and compressed gas is discharged from the cylinder bore through a discharge valve into a discharge chamber during a discharge stroke, and wherein the inclined angle of the swash plate is changed in accordance with the difference between the pressure in the crank chamber and the pressure in the suction chamber to move the piston in the cylinder bore with a stroke determined by the inclined angle of the swash plate to vary the displacement of the compressor, said compressor comprising: a spool disposed adjacent to the swash plate on the drive shaft;   a member biasing the spool toward the swash plate;   a passageway for introducing the gas from the crank chamber to the suction chamber;   said spool being arranged to close the passageway when the swash plate is kept at the minimum inclined angle and open the passageway when the swash plate moves from the minimum angle toward the maximum inclined angle;   said spool having an open end and a closed end, said open end facing the swash plate and said closed end facing away from the swash plate;   said gas containing lubricant oil mist; and   one of said spool open end and said first bearing having a notch to provide a passage for the gas.